[libclang] Expose some target information via the C API.

[emilio]

Summary

This allows users to query the target triple and target pointer width, which
would make me able to fix https://github.com/servo/rust-bindgen/issues/593 and
other related bugs in an elegant way (without having to manually parse the
target triple in the command line arguments).

[emilio]

I'd appreciate if anyone could point me to an appropriate reviewer for this.

Thanks in advance! :)

[arphaman]

Maybe it would be better to introduce a CXTargetInfo type, and change the API to be:

clang_getTranslationUnitTargetInfo
clang_TargetInfo_getTriple
clang_TargetInfo_getPointerWidth

?
This way the TargetInfo functions will be cleanly separated, so we can extend the API easier in the future.

[emilio]

Sounds good to me, will do :)

[emilio]

Updated per comments, I used clang_TargetInfo_dispose following recent APIs instead of clang_disposeTargetInfo, let me know if I should change that.

Also, didn't add a new header for CXTargetInfo, since it's rather small, but can definitely do if needed.

[arphaman]

It looks good, I have a couple of comments:

clang/include/clang-c/Index.h

1573

Please capitalize Info here and in the other parameter lists.

1584

You could mention that the function returns the width in bits.

clang/test/Index/target-info.c

5

NIT: Please put both RUN lines at the top of the file.

clang/tools/libclang/CIndex.cpp

4035

Please add a message to the assert (e.g. && "message").

4048

Please add an assertion message here as well.

[emilio]

Updated per review comments, thanks :)

[arphaman]

Thanks, LGTM

clang/include/clang-c/Index.h

  * \brief The version constants for the libclang API.
  * CINDEX_VERSION_MINOR should increase when there are API additions.
  * CINDEX_VERSION_MAJOR is intended for "major" source/ABI breaking changes.
  *
  * The policy about the libclang API was always to keep it source and ABI
  * compatible, thus CINDEX_VERSION_MAJOR is expected to remain stable.
  */
 #define CINDEX_VERSION_MAJOR 0
-#define CINDEX_VERSION_MINOR 37
+#define CINDEX_VERSION_MINOR 38
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
     + ((minor) *     1))
 
 #define CINDEX_VERSION CINDEX_VERSION_ENCODE( \
     CINDEX_VERSION_MAJOR,                     \
     CINDEX_VERSION_MINOR )

 
 /**
  * \brief An "index" that consists of a set of translation units that would
  * typically be linked together into an executable or library.
  */
 typedef void *CXIndex;
 
 /**
+ * \brief An opaque type representing target information for a given translation
+ * unit.
+ */
+typedef struct CXTargetInfoImpl *CXTargetInfo;
+
+/**
  * \brief A single translation unit, which resides in an index.
  */
 typedef struct CXTranslationUnitImpl *CXTranslationUnit;
 
 /**
  * \brief Opaque pointer representing client data that will be passed through
  * to various callbacks and visitors.
  */
/**
   * \brief Return the memory usage of a translation unit.  This object
   *  should be released with clang_disposeCXTUResourceUsage().
   */
 CINDEX_LINKAGE CXTUResourceUsage clang_getCXTUResourceUsage(CXTranslationUnit TU);
 
 CINDEX_LINKAGE void clang_disposeCXTUResourceUsage(CXTUResourceUsage usage);
 
 /**
+ * \brief Get target information for this translation unit.
+ *
+ * The CXTargetInfo object cannot outlive the CXTranslationUnit object.
+ */
+CINDEX_LINKAGE CXTargetInfo
+clang_getTranslationUnitTargetInfo(CXTranslationUnit CTUnit);
+
+/**
+ * \brief Destroy the CXTargetInfo object.
+ */
+CINDEX_LINKAGE void
+clang_TargetInfo_dispose(CXTargetInfo Info);
+
+/**
+ * \brief Get the normalized target triple as a string.
+ *
+ * Returns the empty string in case of any error.
+ */
+CINDEX_LINKAGE CXString
+clang_TargetInfo_getTriple(CXTargetInfo Info);
+
+/**
+ * \brief Get the pointer width of the target in bits.
+ *
+ * Returns -1 in case of error.
+ */
+CINDEX_LINKAGE int
+clang_TargetInfo_getPointerWidth(CXTargetInfo Info);
+
+/**
  * @}
  */
 
 /**
  * \brief Describes the kind of entity that a cursor refers to.
  */
 enum CXCursorKind {
   /* Declarations */

clang/test/Index/target-info.c

+// RUN: c-index-test -test-print-target-info %s --target=i386-unknown-linux-gnu | FileCheck %s
+// RUN: c-index-test -test-print-target-info %s --target=x86_64-unknown-linux-gnu | FileCheck --check-prefix=CHECK-1 %s
+// CHECK: TargetTriple: i386-unknown-linux-gnu
+// CHECK: PointerWidth: 32
+// CHECK-1: TargetTriple: x86_64-unknown-linux-gnu
+// CHECK-1: PointerWidth: 64

clang/tools/c-index-test/c-index-test.c

if (clang_isDeclaration(typeDeclaration.kind)) {
     PrintCursor(cursor, NULL);
     PrintTypeAndTypeKind(clang_getCursorType(typeDeclaration), " [typedeclaration=%s] [typekind=%s]\n");
   }
 
   return CXChildVisit_Recurse;
 }
 
 /******************************************************************************/
+/* Target information testing.                                                */
+/******************************************************************************/
+
+static int print_target_info(int argc, const char **argv) {
+  CXIndex Idx;
+  CXTranslationUnit TU;
+  CXTargetInfo TargetInfo;
+  CXString Triple;
+  const char *FileName;
+  enum CXErrorCode Err;
+  int PointerWidth;
+
+  if (argc == 0) {
+    fprintf(stderr, "No filename specified\n");
+    return 1;
+  }
+
+  FileName = argv[1];
+
+  Idx = clang_createIndex(0, 1);
+  Err = clang_parseTranslationUnit2(Idx, FileName, argv, argc, NULL, 0,
+                                    getDefaultParsingOptions(), &TU);
+  if (Err != CXError_Success) {
+    fprintf(stderr, "Couldn't parse translation unit!\n");
+    describeLibclangFailure(Err);
+    clang_disposeIndex(Idx);
+    return 1;
+  }
+
+  TargetInfo = clang_getTranslationUnitTargetInfo(TU);
+
+  Triple = clang_TargetInfo_getTriple(TargetInfo);
+  printf("TargetTriple: %s\n", clang_getCString(Triple));
+  clang_disposeString(Triple);
+
+  PointerWidth = clang_TargetInfo_getPointerWidth(TargetInfo);
+  printf("PointerWidth: %d\n", PointerWidth);
+
+  clang_TargetInfo_dispose(TargetInfo);
+  clang_disposeTranslationUnit(TU);
+  clang_disposeIndex(Idx);
+  return 0;
+}
+
+/******************************************************************************/
 /* Loading ASTs/source.                                                       */
 /******************************************************************************/
 
 static int perform_test_load(CXIndex Idx, CXTranslationUnit TU,
                              const char *filter, const char *prefix,
                              CXCursorVisitor Visitor,
                              PostVisitTU PV,
                              const char *CommentSchemaFile) {
fprintf(stderr,
     "       c-index-test -test-inclusion-stack-source {<args>}*\n"
     "       c-index-test -test-inclusion-stack-tu <AST file>\n");
   fprintf(stderr,
     "       c-index-test -test-print-linkage-source {<args>}*\n"
     "       c-index-test -test-print-visibility {<args>}*\n"
     "       c-index-test -test-print-type {<args>}*\n"
     "       c-index-test -test-print-type-size {<args>}*\n"
     "       c-index-test -test-print-bitwidth {<args>}*\n"
+    "       c-index-test -test-print-target-info {<args>}*\n"
     "       c-index-test -test-print-type-declaration {<args>}*\n"
     "       c-index-test -print-usr [<CursorKind> {<args>}]*\n"
-    "       c-index-test -print-usr-file <file>\n"
-    "       c-index-test -write-pch <file> <compiler arguments>\n");
+    "       c-index-test -print-usr-file <file>\n");
   fprintf(stderr,
+    "       c-index-test -write-pch <file> <compiler arguments>\n"
     "       c-index-test -compilation-db [lookup <filename>] database\n");
   fprintf(stderr,
     "       c-index-test -print-build-session-timestamp\n");
   fprintf(stderr,
     "       c-index-test -read-diagnostics <file>\n\n");
   fprintf(stderr,
     " <symbol filter> values:\n%s",
     "   all - load all symbols, including those from PCH\n"
return perform_test_load_source(argc - 2, argv + 2, "all",
                                     PrintTypeDeclaration, 0);
   else if (argc > 2 && strcmp(argv[1], "-test-print-bitwidth") == 0)
     return perform_test_load_source(argc - 2, argv + 2, "all",
                                     PrintBitWidth, 0);
   else if (argc > 2 && strcmp(argv[1], "-test-print-mangle") == 0)
     return perform_test_load_tu(argv[2], "all", NULL, PrintMangledName, NULL);
   else if (argc > 2 && strcmp(argv[1], "-test-print-manglings") == 0)
     return perform_test_load_tu(argv[2], "all", NULL, PrintManglings, NULL);
+  else if (argc > 2 && strcmp(argv[1], "-test-print-target-info") == 0)
+    return print_target_info(argc - 2, argv + 2);
   else if (argc > 1 && strcmp(argv[1], "-print-usr") == 0) {
     if (argc > 2)
       return print_usrs(argv + 2, argv + argc);
     else {
       display_usrs();
       return 1;
     }
   }

clang/tools/libclang/CIndex.cpp

 #include "CXTranslationUnit.h"
 #include "CXType.h"
 #include "CursorVisitor.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticCategories.h"
 #include "clang/Basic/DiagnosticIDs.h"
+#include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/Version.h"
 #include "clang/Frontend/ASTUnit.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Index/CodegenNameGenerator.h"
 #include "clang/Index/CommentToXML.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Lexer.h"
if (isNotUsableTU(TU)) {
     LOG_BAD_TU(TU);
     return clang_getNullCursor();
   }
 
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
   return MakeCXCursor(CXXUnit->getASTContext().getTranslationUnitDecl(), TU);
 }
 
+CXTargetInfo clang_getTranslationUnitTargetInfo(CXTranslationUnit CTUnit) {
+  if (isNotUsableTU(CTUnit)) {
+    LOG_BAD_TU(CTUnit);
+    return nullptr;
+  }
+
+  CXTargetInfoImpl* impl = new CXTargetInfoImpl();
+  impl->TranslationUnit = CTUnit;
+  return impl;
+}
+
+CXString clang_TargetInfo_getTriple(CXTargetInfo TargetInfo) {
+  if (!TargetInfo)
+    return cxstring::createEmpty();
+
+  CXTranslationUnit CTUnit = TargetInfo->TranslationUnit;
+  assert(!isNotUsableTU(CTUnit) &&
+         "Unexpected unusable translation unit in TargetInfo");
+
+  ASTUnit *CXXUnit = cxtu::getASTUnit(CTUnit);
+  std::string Triple =
+    CXXUnit->getASTContext().getTargetInfo().getTriple().normalize();
+  return cxstring::createDup(Triple);
+}
+
+int clang_TargetInfo_getPointerWidth(CXTargetInfo TargetInfo) {
+  if (!TargetInfo)
+    return -1;
+
+  CXTranslationUnit CTUnit = TargetInfo->TranslationUnit;
+  assert(!isNotUsableTU(CTUnit) &&
+         "Unexpected unusable translation unit in TargetInfo");
+
+  ASTUnit *CXXUnit = cxtu::getASTUnit(CTUnit);
+  return CXXUnit->getASTContext().getTargetInfo().getMaxPointerWidth();
+}
+
+void clang_TargetInfo_dispose(CXTargetInfo TargetInfo) {
+  if (!TargetInfo)
+    return;
+
+  delete TargetInfo;
+}
+
 //===----------------------------------------------------------------------===//
 // CXFile Operations.
 //===----------------------------------------------------------------------===//
 
 CXString clang_getFileName(CXFile SFile) {
   if (!SFile)
     return cxstring::createNull();
 

clang/tools/libclang/CXTranslationUnit.h

struct CXTranslationUnitImpl {
   clang::CIndexer *CIdx;
   clang::ASTUnit *TheASTUnit;
   clang::cxstring::CXStringPool *StringPool;
   void *Diagnostics;
   void *OverridenCursorsPool;
   clang::index::CommentToXMLConverter *CommentToXML;
 };
 
+struct CXTargetInfoImpl {
+  CXTranslationUnit TranslationUnit;
+};
+
 namespace clang {
 namespace cxtu {
 
 CXTranslationUnitImpl *MakeCXTranslationUnit(CIndexer *CIdx,
                                              std::unique_ptr<ASTUnit> AU);
 
 static inline ASTUnit *getASTUnit(CXTranslationUnit TU) {
   if (!TU)

clang/tools/libclang/libclang.exports

 clang_ParamCommandComment_isParamIndexValid
 clang_ParamCommandComment_getParamIndex
 clang_ParamCommandComment_isDirectionExplicit
 clang_ParamCommandComment_getDirection
 clang_TParamCommandComment_getParamName
 clang_TParamCommandComment_isParamPositionValid
 clang_TParamCommandComment_getDepth
 clang_TParamCommandComment_getIndex
+clang_TargetInfo_dispose
+clang_TargetInfo_getPointerWidth
+clang_TargetInfo_getTriple
 clang_Type_getAlignOf
 clang_Type_getClassType
 clang_Type_getSizeOf
 clang_Type_getOffsetOf
 clang_Type_getNumTemplateArguments
 clang_Type_getTemplateArgumentAsType
 clang_Type_getCXXRefQualifier
 clang_Type_visitFields

 clang_getTUResourceUsageName
 clang_getTemplateCursorKind
 clang_getTokenExtent
 clang_getTokenKind
 clang_getTokenLocation
 clang_getTokenSpelling
 clang_getTranslationUnitCursor
 clang_getTranslationUnitSpelling
+clang_getTranslationUnitTargetInfo
 clang_getTypeDeclaration
 clang_getTypeKindSpelling
 clang_getTypeSpelling
 clang_getTypedefDeclUnderlyingType
 clang_hashCursor
 clang_indexLoc_getCXSourceLocation
 clang_indexLoc_getFileLocation
 clang_indexSourceFile